This invention relates to an electrosurgical instrument for ear surgery, and in particular, for use in a myringotomy procedure.
Reference is made to our prior issued U.S. Pat. No. 5,741,250, whose contents are incorporated herein by reference. This prior patent describes an improved myringotomy surgical procedure involving an incision of the tympanic membrane that is made to allow ventilation of the middle ear, to permit drainage of middle ear fluid, or to obtain cultures from an infected middle ear. The improved procedure uses a solid wire electrode and electrosurgical apparatus to form the hole in the tympanic membrane. The electrosurgical procedure has the important advantage of being able to cut the tissue while at the same time coagulating the cut tissue causing minimum bleeding. The structure of the novel electrode described in the prior patent used to make the incision prevents the excision depth from exceeding a safe value. In accordance with another feature of that invention, the electrode is uniquely configured to enable the active tip to reach the tympanic membrane via the ear canal passageway and incise the desired tissue while avoiding damage to surrounding tissue.
Recently, a new treatment called OtoScan Laser Assisted Myringotomy (OtoLAM) has been described. It uses a CO2 laser to vaporize an allegedly precisely-sized preset hole in the tympanic membrane without damaging surrounding structures. The preset hole remains open for several weeks allowing ventilation of the middle ear and avoiding the need for grommets to keep the hole open until the middle ear region is adequately drained. The main disadvantage of this procedure is the use of a highly expensive laser instrument requiring training for those physicians that are not familiar with such equipment.
An object of the invention is an improved myringotomy surgical procedure.
We have invented a novel electrode for use in an electrosurgical myringotomy procedure. This electrosurgical procedure using our novel electrode enables physicians to offer to patients a treatment that is efficiently performed, easily learned and thus performed at a significantly reduced price, and with less tissue damage and bleeding compared to procedures done with a knife or needle.
The procedure using our novel electrode is based on forming the same kind of hole in the tympanic membrane as used heretofore, namely, an approximately 2 mm hole in the tympanic membrane, which is large enough to allow adequate drainage from the middle ear over several weeks, but not too large so as to delay healing. However, in accordance with a feature of our invention, electrosurgery is used to punch the hole in the tympanic membrane.
In a first preferred embodiment, a unipolar electrode is used with an electrode end that is hollow and is provided with a circular knife edge whose outer diameter is approximately 2 mm. In a second preferred embodiment, the electrode end is conically tapered from a solid end that has an outer diameter of approximately 2 mm. In both cases, the surgeon places the electrode end against the tympanic membrane and activates the electrosurgical apparatus. The result is to punch a hole in the membrane, by the flow of electrosurgical currents, that is of the same size as the outer diameter of the electrode end.
In comparison with the laser procedure, the electrosurgical equipment is far less expensive and many physicians are already trained in the use of electrosurgical apparatus. Moreover, for those untrained, the training procedure is relatively simple and consumes little time.
In accordance with another feature of the invention, the electrode end is configured with a stop to prevent the punch depth from exceeding a safe value. Preferably, the punch depth does not exceed more than about 70 mm. The latter restriction ensures that the entire depth of the tympanic membrane is penetrated but no further tissue damage will occur. As described in the prior patent, the electrode of the invention is also configured to enable the active tip to reach the tympanic membrane via the ear canal passageway and punch the desired tissue hole while avoiding damage to surrounding tissue.
In a preferred embodiment, our novel electrode is characterized by a straight electrically-insulating portion extending from an insulated handle and terminating in an active bare tip portion. The incision is effected with the bare tip moved by the surgeon in a generally straight path, and the adjacent portions of the tip support and electrode shaft are made insulating to prevent accidental burns to the patient and to allow the physician to use these insulated parts to help position and guide the active tip portion during the surgical procedure. The electrosurgical procedure has the important advantage of being able to punch the tissue while at the same time coagulating the cut tissue causing minimum bleeding. It is preferred that the electrosurgical currents used be above 2 MHz, and preferably above 3 MHz. At these high frequencies, commonly referred to as radiosurgery, cutting is accomplished by volatilizing intracellular fluids at the point of the transmitting electrode contact which is primarily responsible for only small lateral heat spread and thus less damage to neighboring cell layers.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there are illustrated and described the preferred embodiments of the invention, like reference numerals or letters signifying the same or similar components.